PHOENIX — An Arizona sheriff known for aggressively cracking down on illegal immigration has been stripped of some of his special power to enforce federal immigration law, and he claims the Obama administration is taking away his authority for political reasons.

Maricopa County Sheriff Joe Arpaio, whose office faces racial profiling allegations over crime and immigration sweeps in some heavily Latino areas of metro Phoenix, said officials from Washington won't let him renew a deal that let his deputies make federal immigration arrests.

"Let them all go brag that they took away the sheriff's authority. Let them all do that. That doesn't bother me. I don't have an ego. I will continue doing the same thing," the Republican sheriff said, noting he can still enforce state immigration laws. "What has changed, other than the politics and the perception emanating from Washington?"

The U.S. government, which does most of the nation's immigration enforcement, is changing its rules for allowing local police to enforce more expansive federal immigration laws. Nationally, more than 1,000 local police and jail officers have been granted the power since 2002 to make immigration requests and speed up deportations.

Arpaio has more officers with the special powers than any other local police agency in the country. For more than two years, 100 of his deputies have made immigration arrests and another 60 jail officers have identified inmates who are illegal immigrants.

Even though federal officials declined to let the sheriff keep making immigration arrests, Arpaio last week renewed a deal that will let his jail officers determine inmates' immigration status.

Arpaio said federal officials offered no explanation of why his powers were cut in half.

Vinnie Picard, a spokesman for U.S. Immigration and Customs Enforcement, which grants the special powers, declined to comment on the curtailment of Arpaio's powers or whether any of the other 62 participating local agencies across the country have been denied renewals.

Immigration and Customs Enforcement will make no final decisions on the agreements until Oct. 14, which is the deadline for renewing the agreements. So far, at least three agencies have dropped out of the program.

Giving federal powers to local police helps supplement the small staff of federal agents who enforce immigration laws in the country's interior, said Ira Mehlman, a spokesman for the Federation for American Immigration Reform, which favors tougher immigration enforcement.

He said it's hard to tell whether the limits on Arpaio's authority will extend to other agencies and would hamper the movement for local police to confront illegal immigration.

"I suspect there is some effort there to send a warning to other police departments: Don't get too aggressive with this, because we will yank it out from under you," Mehlman said.

Joan Friedland, immigration policy director for the National Immigration Law Center, said the federal government wasn't making a serious attempt to rein in Arpaio, because his jail officers still have the power to question jailed people about their immigration status.

"All he has to do is get people to the jail, rather than being able to question them about their immigration status on the street," said Friedland, whose group advocates for low-income immigrants.

For his part, Arpaio said he plans to continue cracking down illegal immigration by enforcing state laws that prohibit immigrant smuggling and ban employers from knowingly hiring illegal immigrants.

Arpaio said his deputies can still detain suspected illegal immigrants who haven't committed state crimes, as long as his officers call Immigration and Customs Enforcement agents to pick them up.

Critics say some of Arpaio's deputies racially profiled people during immigration sweeps. Arpaio maintains that people pulled over in the sweeps were approached because deputies had probable cause to believe they had committed crimes.

His office is being investigated by the U.S. Department of Justice over allegations of discrimination and unconstitutional searches and seizures.

A September 2008 audit by Immigration and Customs Enforcement said the relationship between that agency and the sheriff's office was good, but noted that most rank-and-file patrol deputies who had the special training and who weren't part of a special smuggling unit had rarely used their federal powers, because they didn't have the experience - or didn't want to take the time - to process illegal immigrants.

The review also noted that the local FBI office received no complaints against officers with the special training.

Arpaio's approach to immigration has frustrated other public officials.

The mayor of Mesa complained in 2008 that Arpaio didn't warn his city of raids by deputies who were looking for illegal immigrants working at his city's library and City Hall.

And as Arpaio's sweeps began to draw heavy criticism in 2008, then-Gov. Janet Napolitano, a Democrat, cut off immigration enforcement dollars to his office.

Napolitano, who as the country's homeland security secretary now oversees the federal government's immigration agencies, had said it wasn't an attempt to change Arpaio's approach to cracking down on illegal immigration. Rather, she said the funding was reallocated to try to clear a backlog of thousands of outstanding felony warrants across the state.

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